I just love the concept of the AccuScribePro -- except that with those beautiful little brass thumb nuts, I find that I must use vise-grips to get it tight enough to not slip -- and slipping is the death of a scribe. Although because the bolt was metric, I had to tap a metric thread in the only wing nuts I could find, it is now a great device with wing nuts in the place of the knurled nuts. See photo. May I recommend a nut change so I could rate this tool as perfect?
After I received your message I tested it and it worked just fine. We sell tens of thousands of them and I maybe heard this three times in 15 years. I'm happy to send you another one to try. Just send your information to Sandi (email@example.com).